title: Growth-phase dependence of susceptibility to antimicrobial peptides in Staphylococcus aureus.
abstract: Bacterial cell surface charge is responsible for susceptibility to cationic antimicrobial peptides. Previously, Staphylococcus aureus dlt and mprF were identified as factors conferring a positive charge upon cell surfaces. In this study, we investigated the regulation of cell surface charge during growth. Using a group of S. aureus MW2 mutants, which are gene-inactivated in 15 types of two-component systems (TCSs), we tested dltC and mprF expression and found that two TCSs, aps and agr, were associated with dltC and mprF expression in a growth phase-dependent manner. The first of these, aps, which had already been identified as a sensor of antimicrobial peptides and a positive regulator of dlt and mprF expression, was expressed strongly in the exponential phase, while its expression was significantly suppressed by agr in the stationary phase, resulting in higher expression of dltC and mprF in the exponential phase and lower expression in the stationary phase. Since both types of expression affected the cell surface charge, the susceptibility to antimicrobial peptides and cationic antibiotics was changed during growth. Furthermore, we found that the ability to sense antimicrobial peptides only functioned in the exponential phase. These results suggest that cell surface charge is tightly regulated during growth in S. aureus.
authors.affiliation: Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Matsuo
authors.affiliation: Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Oogai
authors.affiliation: Department of Bacteriology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima 734-8553, Japan.
authors.forename: Fuminori
authors.initials: F
authors.lastname: Kato
authors.affiliation: Department of Bacteriology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima 734-8553, Japan.
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Sugai
authors.affiliation: Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Komatsuzawa
mesh_terms: D019881:Aminoacyltransferases / Q000235:genetics / Q000378:metabolism; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D053038:Quorum Sensing; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism
chemical_list: C095698:Agr protein, Staphylococcus aureus; D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D002352:Carrier Proteins; C085651:D-alanyl carrier protein, bacteria; D015534:Trans-Activators; D019881:Aminoacyltransferases; C429146:mprF protein, Staphylococcus aureus